1. Field of the Invention
The present invention relates to a medium-frequency radio Transmission system for enabling listening to an AM medium-frequency radio within broadcast wave closed areas such as underground shopping malls, underground parking lots, underground connection passages, underground railways, automobile road tunnels or deep spaces of massive buildings (hereinafter referred to as "tunnel" or "basement" for the sake of explanation).
2. Description of the Related Art
In case of receiving an AM radio wave at the rooftop of an existing high-storied building and transmitting the received radio wave to a basement, prior art has newly built a coaxial cable for transmitting medium-frequency radio waves from the rooftop to the basement within the existing building.
Moreover, in order to reradiate a wave, there was required construction work such as a new inductive line stretched on the wall surface.
In the prior art, since the required construction had to be executed within the existing building, difficult work was generally necessary, and a large amount of expense was required.